Structure-function studies are to be conducted with anthranilate synthase from Serratia marcescens. Group-specific reagents will be used to inactivate the enzyme and identify amino acid residues essential for each of the steps in the reaction: (a) formation of the covalent glutaminyl-enzyme intermediate, (b) transfer of the amide of glutamine from subunit AS II to AS I and (c) reaction of NH3 with chorismic acid catalyzed by AS I. The mechanism of action of the anti-tumor glutamine antagonist L-(alphaS, 5S)-alpha-Amino-3-Chloro-4,5-Dihydro-5-Isoxazoleacetic acid will be studied using anthranilate synthase. Amidophosphoribosyltransferase will be prepared from an overproducing strain of E. coli. Structure-function studies and amino acid sequencing will be conducted.